Add test files for .fhirpath, .fsh, and .feature file types

[Copilot]

Plan: Add Example Test Files for File Types

• Create test-fhirpath.fhirpath file with example FHIRPath content
• Create test-fsh.fsh file with example FHIR Shorthand content
• Create test-feature.feature file with example Gherkin BDD test content
• Verify files are created correctly and follow the pattern of existing test files
• Run validation to ensure no issues introduced (all tests passed)
• Simplify test-feature.feature to only include Scenario Outline with background
• Simplify test-fhirpath.fhirpath by removing observations and age calculation examples

Original prompt

On file-types-test, Can we add the following example test files in workspace-wiki/example/file-types-test/ for the following please:

.fhirpath
.fsh
.feature (Gherkin feature BDD test file)

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[AlexJSully]

@copilot please address the PR comments